2015 Recommended Components Digital Processors

Digital Processors

Editor's Note: The sound of any particular CD transport/digital processor combination will be dependent on the datalink used-see "Bits is Bits?" by Christopher Dunn and Malcolm Omar Hawksford, Stereophile, March 1996, Vol. 19 No.3 (WWW). Unless mentioned, processors are limited to 32/44.1/48kHz sample rates. To be included in Class A+, a digital processor must be capable of handling DSD or 24/96 LPCM data.
We strongly recommend those interested in using a computer as a true high-end digital audio source visit our sister website, www.AudioStream.com, which is edited by Michael Lavorgna.

A+

Antelope Audio Zodiac Platinum: $5500
From the makers of the Class Arated Zodiac Gold comes the Zodiac Platinum, which bundles a D/A processor, headphone amp, and preamp into a small but chunky (6.5" W by 4.4" H by 7.6" D) enclosure. (The similarly chunky Voltikus power supply is slightly less wide.) Like the Gold, the Zodiac Platinum offers PCM performance through 384kHz, but adds DSD64 and 128 via USB (DoP), which it upsamples to DSD256, Antelope Audio claiming direct DSD-to-analog conversion. Technical highlights include FPGA processing for some functions and "Oven-Controlled Clocking," in which jitter is kept low through thermal stabilization of the word clock's crystal oscillator. User controls appear on both the front panel and the remote handset, the former distinguished by a hefty, nice-feeling volume knobalthough JI noted that it "produced a bit of a raggedy zipper sound" through his system when he adjusted the volume. With some musical selections JI noted the Platinum's "slightly thicker bottom end" compared with another premium processor, and with other tracks a thicker sound overall, adding that "both [processors] excelled at creating a transparent path to my power amps." As for the Zodiac's headphone amp, "I'd never heard better sound from my Grado HP1s," JI declared. JA wrapped up: "Overall, the very good measurements of Antelope Audio's Zodiac Platinum indicate excellent digital and analog engineering." (Vol.37 Nos.9 & 10 WWW)

AURALiC VEGA: $3499
The elegant-looking Vega D/A processor is housed in a slim, brushed-aluminum enclosure and has a front panel dominated by a wide, rectangular, yellow-on-black OLED display. The rear panel offers single-ended and balanced outputs, and five digital inputs: transformer-coupled AES/EBU on an XLR, two transformer-coupled coaxial S/PDIFs on RCAs, one optical S/PDIF on TosLink, and a high-speed USB2.0 port. The AES/EBU and S/PDIF inputs handle 16- and 24-bit data with sample rates up to 192kHz; the USB port also operates with sample rates of 352.8 and 384kHz, and will accept DSD64 and DSD128 data. A Sanctuary audio processor upsamples PCM input data to approximately 1.5MHz and 32-bit depth, and implements four reconstruction filters for PCM data and two choices of low-pass filter for DSD data. Though it required several hours from cold before sounding its best, the Vega combined outstanding low-end weight and high-frequency extension with an exceptional sense of space, said JA, who also noted measured performance that was beyond reproach. "It's DSD and digital done right!" he exclaimed. (Vol.37 No.2 WWW)

Ayre Acoustics QA-9: $3950
Housed in the same compact chassis as Ayre's QB-9 USB DAC, the QA-9 is a solid-state A/D converter intended to allow audiophiles to make high-quality rips of their LPs. It uses an Arda Laboratories AT1201 two-channel A/D converter chip and operates at sample rates up to 192kHz, outputting 24-bit data via either a USB 2.0 or AES/EBU connection. Setup was simple and, aside from the tedious task of eliminating LP surface noise, use was straightforward. The Ayre offered smooth highs, a clean midrange, and an excellent sense of space. JA summed up: "When recordings you love have never been issued on a good-sounding CD, it makes sense to rip them with Ayre's QA-9it's the closest thing to a truly transparent audio component I have encountered." He bought the review sample. Pro version ($4750) includes DSD and Word Clock outputs on transformer-coupled BNC jacks and outputs DSD via USB. (Vol.35 No.11, Vol.36 No.4 WWW)

Ayre Acoustics QB-9 DSD: $3250 ✩
The QB-9 is an asynchronous transfer mode, USB-input DAC with Ayre's minimum-phase digital reconstruction filter implemented in Field-Programmable Gate Array. It uses a Texas Instruments TAS1020B chip, supporting sample rates up to 96kHz and word lengths up to 24 bits. High-resolution digital files "popped with life" and were marked by a natural flow and physical impact that allowed WP to form a deeper emotional connection with the music. JA: "Ayre's QB-9 is well engineered, offering excellent performance in both the analog and digital domains, and is not compromised by its having just a USB data input." JI felt the QB-9 exceeded the YBA WD202 and Benchmark DAC1 USB in terms of spatial detail, depth, and width, while adding a touch of seductive clarity. "Wow!" The latest version of the QB-9 uses an XMOS XS-1 microprocessor chip and supports sampling rates via USB2.0 up to 192kHz. Earlier QB-9s can be upgraded for $250. Compared with the Resolution Audio Cantata, the Ayre tended to exaggerate sibilants on some recordings but provided a warmer, fleshier midrange, felt JI. Compared to the NAD M51, the Ayre had slightly greater punch and better dynamic edges. Compared to the much more expensive MSB Diamond DAC IV, the QB-9 had a very slightly more aggressive midrange, but otherwise held its own, said JI. Current production as of mid-2013, auditioned by AD in connection with his AX-5 review in Vol.36 No.7, uses an ESS Sabre DAC chip, offers improvements to the USB chip power supply, and will decode DSD data. Stereophile's "Joint Digital Source" and "Overall Component" of 2009. (Vol.32 No.10, Vol.33 No.6, Vol.34 Nos.7 & 11, Vol.35 Nos.7 & 10 WWW)

Benchmark Media Systems DAC2 HGC: $1995 $$$
Although similar in appearance to previous Benchmark models, with a front-panel volume control and two 1/4" headphone jacks, the new DAC2 HGC uses four 32-bit ESS Sabre DACs, run in balanced configuration, for a significantly lower noise floor; has a new Hybrid Gain Control (HGC) for volume attenuation, which combines active analog gain control and passive low-impedance attenuators in the analog realm with a 32-bit digital DSP gain control for digital signals; and provides front-panel displays for both sample rate and word length. Though it lacks a balanced AES/EBU input, the DAC2 HGC offers two analog inputs and five digital inputs: two optical, two RCA coaxial, and one asynchronous USB that handles resolutions up to 192kHz as well as DSD64. It had a pleasantly forward sound, with smooth highs, a solid bottom end, and excellent image separation, said EL. Compared to the Auralic Vega, the Benchmark had a similarly smooth top end, but lacked the Vega's sweet midrange and outstanding portrayal of space, said JA. JI noted the DAC2's good scale and sense of ambient space, but found it lacked focus compared to the considerably more expensive MSB Analog DAC. (Vol.37 No.2 WWW)

Bricasti Design M1 DAC: $8595
With first-class fit'n'finish and uncluttered exterior design, the dual-mono M1 DAC measures a rack-friendly 17" W by 2" H by 12" D and weighs 12 lbs. It offers four digital inputs (S/PDIF, AES/EBU, BNC, optical), accepts sampling rates up to 192kHz, and, as of 2013, adds a USB input, volume control, remote control, and DSD decoding. The Bricasti's fast, detailed, powerful sound made the much less expensive Musical Fidelity M1DAC seem veiled, muffled, and slow, said JM. "The best digital playback I have heard," he concluded. Compared with the Weiss DAC202, the Bricasti was less forgiving of poorly recorded material, but had bigger, deeper, better-defined low frequencies; compared with the dCS Debussy, the Bricasti sounded very slightly warmer and was very slightly more transparent, said JA, who also praised the M1's state-of-the-art measured behavior. A firmware update (free to registered owners) adds minimum-phase digital filter options, digital phase inversion, and a digital volume control. Compared to its previous filter set, the Bricasti's minimum-phase sound was much richer, with more body, more coherence, and less grain, said JM. Used as a line source in place of Parasound's Halo JC 2 preamp, the Bricasti produced a more coherent sound, with deeper, tighter, more powerful bass. "My personal best just got better," JM concluded. Now ships with asynchronous USB input (not yet auditioned), and will decode DSD data. Production in 2013 replaces the switch-mode power supply of the M1's digital-routing section with a linear supply based on a custom-wound transformer. With the new power supply in place, JM heard improved bass extension and greater overall clarity. Owners of original M1s (made prior to March 2013) can have their units updated for $200. In 2014, Bricasti offered to M1 owners even more additional refinements: a remote-control kit, involving a separate infrared receiver that plugs into the rear panel ($500 for M1s presently in service; included in the price of new units); a changeover, performed at the factory, from multiple glass-and-wire fuses to a master circuit breaker ($150); and an upgrade, also done at the factory, to DXD and DSD64/DSD128 capabilities ($400). As impressed as he was by the last, JM remained philosophical: "the fact that Bricasti's M1 can now play DSD and DXD files is less important than the fact that its playback of plain old 'Red Book' 16-bit/44.1kHz audio is so compelling that I, for one, don't feel shortchanged when a good recording is not 'high-resolution.'" He observed that, yet again, his personal best in digital playback just got better. (Vol.34 No.8; Vol.35 Nos. 2, 3 & 9; Vol.36 No.7; Vol.37 No.12 WWW)

dCS Debussy: $11,499 ✩
The slim, sleek Debussy D/A processor has a digital volume control, offers a full range of digital inputs including a true asynchronous USB port, and uses the latest version of dCS's Ring DAC. The USB input was upgraded in the summer of 2011 to handle 176.4 and 192kHz data and in the summer of 2012 to handle DSD data. Though it lacked the sophistication of dCS's more expensive Scarlatti system, the Debussy had a fast and delicate sound, with powerful bass, dramatically solid, three-dimensional images, sensational rhythmic drive, and outstanding dynamics, said MF: "A very easy and enthusiastic recommendation." JA agreed: "It was a pleasure to test such a superbly engineered product." Compared with the Weiss DAC202, the Debussy offered greater resolution, transient snap, and low-bass weight, but lacked midrange warmth and overall body, said EL. Compared with the Bricasti M1, the Debussy was slightly less transparent, said JA; compared to the Classé CP-800, the Debussy offered more ambience and propulsive drive but lacked some lower-midrange energy. Compared to the MSB Diamond DAC IV, the Debussy sounded refined and very polite but lacked image precision and spatial depth, said JI. (Vol.34 Nos.1 & 12; Vol.35 Nos.2, 9, & 10 WWW)

Grace m905: $3495
From the pro-audio world comes the Grace Designs m905 Monitor Controller: a combination line stage, D/A converter, and headphone amplifier designed as a control center for music playback in a recording studio. As befits its provenance, the m905 is rack-mountable, with most of its controls built into an umbilical-connected, iPad Minisized remote that, according to JM, exuded an "Authentic German Engineering" level of quality, even though Grace Designs is based in Colorado. The m905 is built around the Burr-Brown PCM1798 DAC chip, plus an XMOS USB receiver, and it offers, via the DoP standard, DSD streaming: the first product from Grace Designs to do so. Already a fan of the "ever-so-slightly euphonic" Grace m903which was Stereophile's Headphone Product of the Year for 2012JM was "taken aback at how much better the m905 sounded," and quantified the depth of his delight at the new model's DSD capabilities with two words: "Woober Joobers!" He said that, all in all, the m905 is "among the most impressive pieces of audio gear" he has ever evaluated. (Vol.37 No.4 WWW)

Luxman DA-06: $4990
Among the earliest and most notable products to emerge from the burgeoning world of DSD streaming, the Luxman DA-06 is a full-size D/A processor built around a Burr-Brown PCM 1792A 32-bit converter chip. The DA-06 supports 2.8224 and 5.6448MHz DSD files and, via its USB input, PCM files up to 32-bit/384kHz. Front-panel controls include the ability to select among three different PCM filters and between two sets of DSD rolloff characteristics, as well as to invert absolute signal polarity on the fly. AD, who acknowledges "DSD's prowess at communicating the subtleties of musical flow," observed that the Luxman sounded "generously explicit, [with] musical and sonic details in abundance and . . . a soundfield notable for its openness and general lack of murk. Still, the DA-06 had good substance, with a tonal character that was slightlyalmost imperceptiblywarm and round." In his measurements, JA noted that the Luxman's low levels of harmonic and intermodulation distortion are offset somewhat by marginally poorer-than-expected jitter and noise-floor numbersyet he declared that, overall, "the DA-06's measured performance is simply superb." AD's conclusion: "a damn fine-sounding D/A converter with virtually all music." (Vol.37 No.7 WWW)

MSB Analog DAC: $6995
The MSB Analog DAC combines a high-tech chassis machined from a solid billet of aluminumit stands less than 1" tall yet weighs nearly 30 lbs!with a circuit architecture that allows the buyer to select among five digital-input options, two power supply options, a WiFi option, and morecombinations of which can bring the price to just under $12,000. (For $6995, you get one digital input and the stock power supply.) The Analog DAC supports PCM and DSD up to 384kHz, employs a custom-designed, linear-phase apodizing digital filter, and offers single-ended and balanced analog outputs. JI was impressed with the MSB's "thereness," observing that, "With a DAC like the MSB, you get a sense of someone hitting Play on a big reel of wide-track analog tape, after being fed by live mikes in a room." Notwithstanding a couple of performance glitches, both solved by in-the-field firmware updates, JI found it difficult to part with his review sample: "It notched my system up to a place where almost all digital sources had an organic, natural presence without sacrificing the accuracy and detail present in the best recordings." JA noted that high-level signals produced some low-level distortion products, but otherwise found the MSB rare in being "so well thought out and so well engineered." Optional Volume Control: $995. Optional Analog Power Base: $2995. UMT Plus: $5995. Optional Dual Signature Power Base: $4995. (Vol.37 No.4 WWW)

MSB Diamond DAC V: $29,995
The Diamond DAC V (called IV when reviewed) is a solid-state, remote-controlled D/A converter with a volume control, a top-panel iPod dock, and an auxiliary analog input. In addition to its balanced and single-ended outputs, the MSB provides a complete array of digital inputs: coaxial S/PDIF (RCA and BNC), TosLink, AES/EBU, MSB Network, and USB 2.0 digital inputs operating in isochronous asynchronous mode with 24-bit word length and sample rates from 44.1 to 384kHz. Options, as reviewed, include: FemtoSecond Galaxy Clock (now included as standard, $4995 for retrofit to older Diamond DACs), Diamond Stepped Attenuator ($2995), USB2.0 384kHz input ($1395), and Diamond Power Base ($5995). With its smooth and detailed midrange, pinpoint imaging, and superb spatial performance, the Diamond DAC IV produced "the best digital sound" JI had ever heard in his system. JA was similarly impressed by the MSB's measured performance. Current Diamond V version is exactly the same as the 2014 Select, which was $75,000. Customers can upgrade from the older Diamond Plus series to the Diamond V series for $6995. (Vol.35 No.10 WWW)

NAD M51 Direct Digital: $1999 $$$
The M51 is an attractive, full-width D/A converter with a digital volume control and useful front-panel vacuum-fluorescent display that indicates input, volume status, and sampling rate. It offers AES/EBU, coaxial, optical, USB, and two HDMI inputs, as well as analog (one pair each single-ended and balanced) and digital (HDMI) outputs. While all of the NAD's inputs can handle PCM audio data of resolutions up to 24-bit/192kHz, the M51 converts everything it receives to a pulse-width-modulation (PWM) signal at a sampling rate of 844kHz, controlled by a clock running at 108MHz. The NAD had a "wonderfully detailed and revealing sound," said JI. JA noted measured performance that was "almost beyond reproach." Compared to the Auralic Vega, the NAD produced a cleaner, leaner, airier, less forgiving sound, said JA, though he still highly recommends the M51 as a great value for the price. Readers have reportedand JA has now confirmedthat the M51's earlier v.1.39 firmware offers a better, "fatter" sound than the later v.1.41, probably die to a 1dB higher output; later versions of the M51 can be easily "rolled back." to v.1.39. (Vol.35 No.7; Vol.37 Nos.2 & 5 WWW)

PS Audio PerfectWave DirectStream: $5999.95
Instead of an off-the-shelf chipset, PS Audio's first DSD processor uses original code written by hand into a field-programmable gate array (FPGA)the result being a system that converts all incoming data to double-rate DSD. In addition to asynchronous USB, digital inputs include RCA, TosLink, and HDMI, and both single-ended and true balanced analog outputs are provided. The DirectStream is built on a cast-alloy chassis with a glossy MDF topand a touchscreen from which all user controls can be worked. (A remote handset is included.) Firmware is user-updateable, as AD discovered while reviewing the DirectStreamduring which time he noted its "excellent pacing, flow, correctness of pitch relationships, and the like, as well as a consistently smooth and slightly laid-back sound." With some files, AD found the DirectStream just a little too laid-backa condition mitigated in part by that firmware updatebut found its musicality beyond reproach. JA observed that the DirectStream "measures superbly well" in many ways, but was troubled by its poor linearity at low frequencies and its "ultimate lack of resolution" with hi-rez files. But he admits that its sound quality is still very satisfying. In his Follow-Up, RDwhose listening is centered more around discs than downloadstried the DirectStream DAC with PSAudio's PerfectWave Memory Player transport ($3995), and observed that, "listening to familiar recordings . . . I heard more musical detail from them than I previously had. This detail was not a matter of exaggerated treble, which can give an impression of increased detail, but was genuinely higher resolution manifested by greater differentiation among the sounds of instruments and rhythmic patterns." Subsequent to that audition, RD received and installed in the DirectStream DAC a new firmware upgrade, bringing his unit to v.1.2.1. His verdict: "The latest firmware represented a major improvement over the one that I and Art Dudley and Michael Lavorgna had. Soundstages were now deeper and wider, and well outside the speakers' positions with some recordings; and images on those stages were now more 'rounded,' more three-dimensional. The bass was cleaner, with better-defined transients." Following the firmware update to v.1.2.1, JA retested the DirectStream and found evidence of a lower noise floor, increased low-level linearity, and a dramatic reduction in low-frequency distortion. Said JA: "Kudos to PS Audio for designing a product so that its performance can so easily be upgraded by its customers." (Vol.37 No.9, Vol.38 Nos. 2 & 3 WWW)

Weiss DAC202: $7287 ✩
Made in Switzerland, the DAC202 is a digital-to-analog converter with an onboard volume control, a headphone amp, and a FireWire input. It offers AES/EBU, S/PDIF, and TosLink connections; uses an ESS9018 DAC chip; and can accept data resolutions up to 24-bit/192kHz. The Weiss had a smooth, delicate overall sound with a forgiving top octave, but lacked bass extension, jump factor, and involvement, said EL. Nevertheless, he concluded: "I think the Weiss DAC202 can easily offer Class A performance, especially for the audiophile who prizes its graceful, organic musicmaking." Compared with the Bricasti M1, the Weiss had a smoother overall sound but lacked bass definition, said JA. On the test bench, the Weiss proved the best-measuring D/A processor in JA's experience: "It just doesn't get any better than this!" DAC202U ($8554, not auditioned) offers USB input. (Vol.35 Nos.1 & 2 WWW)

A

Abbingdon Music Research DP-777: $4995 $$$ ✩
Built into a large (17.7" W by 4.7" H by 14.6" D), well-braced, beautifully finished aluminum chassis, the tubed DP-777 is a versatile digital-to-analog processor that incorporates separate chips for handling high-resolution files and "Red Book" CDs. It offers the user choices of: five digital filters (two "Red Book," three hi-rez), six sampling rates, two jitter-reduction settings, sampling rates up to 192kHz, and word lengths up to 32 bits. There are five types of digital input jacks; two types of analog output jacks; and an optional volume control and analog inputs, to allow the DP-777 to be used as a conventional preamplifier. A Russian 6H11P dual-triode is used as an S/PDIF input amplifier on two of the DP-777's digital inputs. AD: "The DP-777's characteristic sound was one of openness, a generous sense of scale, detail without artifice, and a barely perceptible but undeniably consistent timbral warmth." JA was disappointed by the DP-777's measured performance in HD mode. (Vol.35 No.3 WWW)

Antelope Zodiac Gold: $3895
The Gold version of Antelope's Zodiac D/A headphone amp is housed in a gold-toned, shoebox-sized chassis and can accept PCM digital data sampling rates up to 384kHz. It offers multiple digital and analog input and output options, has a front-panel Mono button, two front-panel headphone jacks, and comes with a stylish, all-metal remote control. Compared to the more expensive Bricasti M1, the Zodiac Gold lacked precision, control, and treble extension, but nevertheless offered a full-bodied, musically satisfying, emotionally engaging sound with a warm midrange and a delicate treble, said JM. Voltikus power supply adds $995 if purchased separately. (Vol.34 No.10 WWW)

Arcam FMJ D33: $3199.99
Designed and manufactured in the UK, Arcam's FMJ D33 is a remote-controlled D/A processor with three digital filters. It handles resolutions up to 24-bit/192kHz and offers coaxial and TosLink S/PDIF inputs, an AES/EBU input, two USB ports, and a Type A port for iDevices. Though its treble had a bit too much bite, the D33's overall sound was clean and clear, with excellent low-frequency definition and extension, said JA. Switching to Filter 1, a minimum-phase filter with a fast rolloff, produced high frequencies that were better integrated with the midrange and bass. JA noted impressive measured performance. In April 2013, JA used the D33 as the vehicle for a new digital test and decided that its apodizing filter is among the best-sounding he's tried. (Vol.36 Nos.2 & 4 WWW)

Bel Canto e.One DAC3.5VB Mk.II: $3495 ✩
Like other Bel Canto products, the e.One DAC3.5BV is roughly half the width of a typical audio component and boasts a black-painted steel chassis with a beautifully milled faceplate of naturally finished aluminum. It accepts resolutions up to 24-bit/96kHz and offers a wealth of inputs: RCA and BNC digital, balanced AES/EBU digital, TosLink, ST fiber-optic, and a single pair of analog RCA jacks. While its D/A section is similar to that found in Bel Canto's e.One DAC3, the DAC3.5VB has revised jitter-rejection circuitry for improved performance with high-jitter sources. Meanwhile, the optional VBS1 power supply ($1495) provides 12V DC and adds heroic LC filtering and energy storage. EL was most impressed by the Bel Canto's ability to produce big soundstages with exceptionally quiet backgrounds. Adding the VB-REF power cable ($495) opened up those stages even more, reduced treble grain, and lowered the perceived noise floor. On the test bench, the Bel Canto exhibited high resolution and low jitter. The Bel Canto traded the sweet tone of Weiss's DAC202 for greater overall clarity and cleaner highs; compared with the dCS Debussy, the Bel Canto lacked some bass, but offered a warmer, more musical sound, with blacker backgrounds and fleshier images, said EL. Review was of original version; Mk.II has improved power supply and a master clock with lower phase noise. Compared to the Benchmark DAC2 HGC, the Bel Canto had a more laid-back overall sound, with a larger soundstage and better image separation, said EL. (Vol.34 No.6; Vol.35 No.1; Vol.37 No.2 WWW)

Benchmark Media Systems ADC1 USB: $1795 $$$
Housed in the same small case as Benchmark's DACs, the ADC1 is a 24-bit USB A/D converter with a Texas Instruments TAS1020B USB chip and a 128x-oversampling, delta-sigma AKM 5394 A/D converter chip. It offers a pair of balanced analog inputs on XLRs, two unbalanced AES/EBU Aux outputs on BNC jacks, a USB Type-B port, a Main TosLink output working in either S/PDIF or ADAT format, a Main balanced AES/EBU output on an XLR, and word-clock input and output on BNCs for use in multichannel systems, slaved to other converters. Though it lacked the Ayre Acoustics QA-9's delicately drawn soundstage, the Benchmark produced a natural, coherent overall sound, with clean high frequencies and weighty, extended lows, said JA, who also noted superb measured performance. (Vol.37 No.2 WWW)

Benchmark DAC1 HDR: $1295 ✩
Features two front-panel headphone jacks, RCA single-ended and XLR balanced analog line outputs that are switchable between line level, trim-pot set, calibrated level, and variable level. Compared to the three-times-more-expensive Marantz SA-14, JM found the original DAC1 to be "slightly more articulate in the musical line, and slightly more detailed in spatial nuances, particularly the localization of individual images in space, and in soundstage depth." A terrific value, feels JA, thinking the DAC1 is a great way of getting modern sound from a DVD player or an older CD player. JA discovered superb measured performance in both the DAC1's digital and analog domains, and decided, "Whether considered as a standalone D/A converter or a versatile headphone amp, Benchmark's DAC1 is an audiophile bargain." The USB version adds a USB 1.1 port to take audio data directly from a computer at sample rates up to 96kHz and bit depths up to 24. Additional improvements over the standard DAC1 include: two gain settings for the headphone amp, a defeatable muting of the line outputs, and high-current output drivers for the XLR and RCA outputs. Used as the primary digital source in JA's system, the DAC1 USB offered a "very appealing" sound, with smoother highs and less grain than the original DAC1. Problems arose with the original sample, however, when using the Benchmark to play back 16-bit files from either a PC or a Mac via the USB connection. Subsequent modification of the DAC1 USB's firmware has eliminated dropouts of 16-bit audio data below 70dBFS while preserving the Benchmark's "superbly transparent soundstaging, clean high frequencies, and powerful lows," said JA. Compared to the YBA WD202, the Benchmark via USB had a slightly more forward, natural, precise sound, said JI. DAC1 PRE (discontinued in January 2013) adds a pair of unbalanced analog RCA inputs. It offered a sound that was "slightly toward the lean side of neutral," said ST. In terms of dynamic shadings, tonal color, and control flexibility, the Benchmark's performance was "remarkably close" to that of the best dedicated line-stage preamps. JA agreed: "As an analog preamplifier, the DAC1 PRE is about as good as it gets, measurement-wise." The DAC1 HDR offers slightly better build quality than earlier models and adds a motorized Alps volume potentiometer. National Semiconductor LM4562 op-amps are used throughout its analog stage, as well as Teflon RCA connectors. Though it maintained the tonal balance of earlier DAC1s, the HDR proved more musical and engaging, with a bigger soundstage, better solidity and separation of instruments in the stereo image, and better treble resolution, said EL. The Benchmark was tonally similar to the Bel Canto e.One DAC3.5VB, but lacked the more expensive DAC's high-frequency clarity, bass depth, and soundstage size, felt EL. Compared to the NuForce CDP-8, the DAC1 produced a slightly richer sound with more air and less bite, said WP. Compared with the Peachtree iDac, the Benchmark offered greater clarity and control but was less forgiving of poor recordings, said JI; compared with the Musical Fidelity M1CLiC, the Benchmark offered greater resolution and accuracy; compared to the NAD M51, the Benchmark was just as detailed, but lacked some finesse and body, said JI. Compared to the much more expensive MSB Diamond DAC IV, the DAC1 USB produced a harder, more congested midrange, and had trouble controlling complex imaging, said JI. As of 2015, only the DAC1 HDR is still available. (DAC1, Vol.26 No.7, Vol.27 No.5, Vol.29 No.4, Vol.33 No.11 WWW; DAC1 USB, Vol.31 Nos.1, 7, & 10, Vol.32 No.3, Vol.33 Nos.6, 9, & 11, Vol.35 No.7 WWW; Vol.34 Nos.6 & 10, Vol.35 Nos.3 & 10 WWW)

Cambridge Audio Azur 851D: $1649 $$$
Designed in the UK and manufactured in China, the Cambridge Azur 851D DAC-preamplifier is well-finished and somewhat surprisingly solid for its price range. It upsamples everything to 24-bit/384kHz, and most of its inputs can handle 24/192 datastreams. The Azur 851D also has a headphone jack, three switchable filter settings, a choice of balanced and single-ended outputsand, for the fun of it, Bluetooth wireless connectivity. It also has a sophisticated user interface, addressable by both its menu-driven front-panel controls and its comprehensive remote handset. In JI's words, "the Cambridge Audio Azur 851D has bang for the buck all over the place. It approached the sound of DACs costing four times as muchclosely enough, I feel, to satisfy most audiophiles on a budget." After the 851D left his test bench, JA observed, "The Cambridge Audio Azur 851D's measured performance is never short of superb. The fact that it can offer this level of performance for $1500 puts many more-expensive processors to shame." In his Follow-Up, AD was put off by the Azur's "needlessly complex" control panel, but impressed all to hell and back by its musicality: "The Cambridge 851D is, indeed, a killer of giants. It is a D/A converter that uses its high resolution not to add amusical filigree or spatial puffery, but to enhance musical flow and drama. It really is that good. (Vol.37 No.12, Vol.38 No.2 WWW)

CEntrance DACmini CX: $799.99 $$$
With a footprint to match Apple's original Mac mini, the CEntrance DACmini CX is a solid-state D/A processor, line preamplifier, and headphone amp with an external power supply. Its slim front panel holds an input selector, volume control, and 1/4" headphone jack. The DACmini's AKM 4396 DAC chip accepts signals with word lengths up to 24 bits and sample rates up to 192kHz via its coaxial input, and up to 96kHz via USB. Though it lacked the resolution and bass impact of the much more expensive dCS Debussy, the DACmini offered a big, bold sound that was forgiving of poorly recorded material. Compared to CEntrance's own DACport, the DACmini offered better low-bass control and greater treble extension, said EL. Mods available for no charge: Black-anodized finish; Headphone Linearity; Rock and Roll; Variable Output. (Vol. 34 No.12 WWW)

Classé CP-800: $6000
D/A preamplifier with serial and asynchronous USB inputs. (See "Preamplifiers.") On the test bench, the Classé's digital input showed about two bits' worth less resolution than the current state of the art, but was excellent-sounding. (Vol.35 No.9 WWW)

Electrocompaniet Classic ECD 2: $3099
The slim (18.3" W by 3" H by 12.4" D), attractive ECD 2 D/A processor has a black-painted steel case and a thick acrylic front panel. It lacks an AES/EBU input, but offers one pair each of balanced and unbalanced analog outputs and five digital inputs: asynchronous USB 2.0, and two each coaxial and optical S/PDIF. A large XMOS chip handles the USB input, and the digital data are fed to a Burr-Brown SRC43921 upsampler chip, which then feeds two Cirrus 4398 multi-bit, delta-sigma DAC chips. Though the ECD 2 lacked some soundstage depth and leading-edge articulation, it had a clean, clear, robust overall sound, with authoritative low-frequency control, said JA, who also praised its nearly state-of-the-art measured performance. (Vol.36 No.12 WWW)

Halide Design DAC HD: $450 $$$
The DAC HD is a solid-state, bus-powered, plug-and-play digital-to-analog converter with tethered input and output cables. The circuitry, all surface-mount, is contained in a small (1.875 cubic inches), black-anodized, machined-aluminum enclosure, and is carried on a small double-sided printed circuit board. The input cable is Wireworld's Starlight USB (2m is standard; other lengths available); output is via two 6" lengths of silver-conductor cable terminated in Eichmann Silver Bullet RCA plugs. The 24-bit Texas Instruments TAS1020B USB interface chip operates in isochronous asynchronous mode with sample rates up to 96kHz. The DAC HD had an "analog-like ease to its sound," coupled with excellent reproduction of recorded space, said JA, who also noted "superb digital audio engineering." Compared to the AudioQuest DragonFly and CEntrance DACport LX, the Halide DAC HD offered slightly smoother highs and produced more spatial depth with stereo recordings, said JA. AD noted that "the affordable and consistently listenable Halide DAC HD . . . has become my USB reference during the past year." He considers the US-made Halide to be among the greatest bargains, if not the great bargain, in perfectionist audio. (Vol.35 Nos.8 & 10, Vo.37 No.7 WWW)

Halide Design USB-S/PDIF Bridge: $395 ✩
In this utilitarian-looking USB-S/PDIF converter, a 6' USB cable terminates in a 3"-long black aluminum tube with, on its other end, either a 75 ohm BNC plug or an Eichmann Silver Bullet RCA plug. The Bridge gets its 5V power from the USB bus and feeds the USB datastream to a Texas Instruments TAS1020B receiver chip, enabling the Bridge to operate in asynchronous mode without the host computer having to install a driver program. It operated properly at sample rates of up to 96kHz, and produced a very clean datastream free from timing uncertainty; and with its relaxed, grain-free sound, the Bridge excelled at conveying recorded ambience and low-level detail, said JA. (Vol.33 No.12 WWW)

Lector Strumenti Digitube S-192: $3195
The full-width (16.9") Lector Strumenti Digitube S-192, which AD described as well built and well styled "without silly excess," is a D/A converter whose only user control, apart from its power switch, is a pushbutton that selects among its five digital inputs: RCA, BNC, TosLink, XLR (for AES/EBU), and USB. Its Japanese AK4397 DAC chip provides 32-bit performance at up to 192kHz, and it has an analog (non-switching) power supply and, in its analog output section, a pair of ECC81 dual-triode tubes. Using the Digitube primarily as a USD processor with his iMac and his decidedly tube-friendly music system, AD found that it offered "a near-analog portrayal of . . . colors and textures" and excellent impact and detail resolution, although its sense of scale was bested by the far less expensive Halide DAC HD. Yet in measuring the Digitube, JA noted "truly dreadful measured performance in the digital domain, along with [a] disappointing showing in the analog domain"in light of which, greater-than-usual buyer circumspection seems appropriate. "Class A, for special tastes only," sums up AD. (Vol.37 No.6 WWW)

M2Tech Young DSD: $1599
Elegant and modern in appearance, the M2Tech Young is a DC-powered D/A processor with a simple aluminum case, a recessed front panel, and a large alphanumeric display. It uses a Burr-Brown PCM1795 DAC chip with a custom oversampling minimum-phase filter. It handles resolutions up to 32 bits via USB (24 bits via S/PDIF or AES/EBU), and sample rates up to 384kHz via USB (192kHz via S/PDIF or AES/EBU). While the Young lacked some accuracy and precision, it nevertheless managed an excellent balance of detail and warmth, said JI. Review was with the Palmer Power Station battery power supply, now replaced byt he Van der Graaf low-noise power supply ($1199). Adding the Palmer resulted in significantly more focus and clarity. "The M2Tech combo seduced me," JI concluded. Current version will decode DSD128. (Vol.36 No.5 WWW)

Musical Fidelity M6DAC: $2999
The M6DAC is a remote-controlled D/A processor with two user-selectable digital filters. (JA admits to hearing no difference between the M6DAC's digital filters, which don't measure differently below 60kHz.) It offers a full complement of digital inputs (balanced AES/EBU, TosLink and coaxial S/PDIF, asynchronous USB-B, and Bluetooth operating with aptX decoding) and uses a dual-differential, 8x-oversampling, 24-bit delta-sigma DAC chip with asynchronous upsampling on all inputs to 192kHz. Music played via Bluetooth ultimately sounded flat and uninvolving, but was fine for casual listening. From its USB or AES/EBU connections, however, the M6DAC produced clean highs, a natural midrange, and authoritative bass. "Musical Fidelity's M6DAC is a superb-sounding, versatile D/A processor," JA concluded. (Vol.36 No.6 WWW)

Musical Fidelity V90-DAC: $299 $$$
Intended as a replacement for their V-DACIIitself one of ST's longtime reference componentsMusical Fidelity's V90-DAC is housed in the same 6.6" by 4" by 1.8" brushed-aluminum case that characterizes the rest of the V90 line. This 24-bit converter, which uses a 32-bit Burr-Brown PCM1795 DAC chip, delivers up to 192kHz performance through its single coaxial (RCA) input and up to 96kHz through its USB and two optical TosLink inputs. According to ST, compared with its predecessor, "the V90-DAC offers still greater low-level resolution, superior dynamics, and fatigue-free listening." JA took the V90-DAC for a spin, going so far as comparing it with his current reference, the Auralic Vega. He noted the MF's combination of smoothness, naturalness, and detail, combined with good spatial propertiesbut he felt the V90-DAC was lacking, by comparison, in momentum and bass power. JA's measurements uncovered "a strange rise in the noise floor around the 19 and 20kHz tones, in only the right channel"; otherwise, the V90-DAC "definitely punched above its weight on the test bench." (Vol.37 Nos. 4 & 8 WWW)

Mytek Stereo192-DSD-DAC: $1595
The Stereo192-DSD is a two-channel DAC with S/PDIF, AES, TosLink, FireWire, and two USB (1.1 and 2.0) digital inputs; a preamp version adds analog RCA inputs and outputs and XLR analog outputs. KR stacked three Myteks for multichannel DSD playback. The sound was clean and engaging, with brilliant highs, potent bass, and outstanding reproduction of space; compared to the Oppo BDP-105, the Mytek stack produced a more vivid, immediate, and open sound, with a wider and slightly more forward soundstage, said Kal. "A successful proof of concept," he concluded. (Vol.36 No.7 WWW)

B

AudioQuest DragonFly v1.2: $149 $$$
Using Gordon Rankin's "Streamlength" asynchronous USB technology and made in the US, the DragonFly measures 2.5" long, weighs three-quarters of an ounce, streams up to 24 bits and 96kHz, and plugs directly into the user's laptop or desktop computer. Included among its 107 internal parts are a Texas Instruments TAS1020 controller chip, a 24-bit ESS Sabre DAC, and a Burr-Brown headphone amp with a 64-step analog volume control. One-millimeter microdot LEDs enable the dragonfly emblem on the DAC's zinc-alloy case to change color in accordance with the sampling rate of the file being played: green (44.1kHz), blue (48kHz), amber (88.2kHz), and purple (96kHz). The original DragonFly had a well-balanced overall sound, with good tonal color and superb texture, but lacked the spatial depth and timbral sophistication of the Halide DAC HD, said AD. "Class B with two thumbs up," sez SM of the first version, adding that when used to drive Skullcandy's Navigator headphones, the DragonFly created a big, bold sound with rich tone color and tight image focus. Aside from some small, tidy certification markings on its backside, the DragonFly v1.2 is identical in size, shape, and functionality to the original model. Upgrades include a revised power supply and a simplified, more direct signal path between the DAC and headphone module. Where the original excelled in clarity and detail, v1.2 added a richer, more colorful midrange, improved spatial abilities, and a greater sense of ease, said SM. (Vol.35 No.10; Vol.36 No.8; Vol.37 Nos.3 & 4 WWW)

Cambridge Audio DacMagic XS: $199 $$$
As with the well-known AudioQuest DragonFly and other portable models, the UK-designed, Chinese-built Cambridge Audio DacMagic XS gets all the power it needs from the USB bus of the associated computer; unlike those productsbut like the Meridian Explorerthe DacMagic XS connects to its host not with an integral USB plug, but via a USB mini-B jack and 6"-long cable (included): an arrangement described by SM as "inelegant" and "awkward." Still, the DacMagic XS, which uses the ESS Sabre ES9023 DAC chip and supports sampling rates of up to 192kHz when connected as a USB 2 device, impressed SM with sound that was, "in a word, glorious." The Cambridge DAC offered "greater top-end clarity and extension than the [AudioQuest DragonFly], but with a richer, more relaxed overall sound than the [Audioengine D3]." (Vol.37 No.4 WWW)

CEntrance DACport LX: $199.99 $$$ ✩Centrance DACport: $249.99 ✩
USB bus-powered D/A processor with or without (LX) volume control. See "Headphones & Headphone Accessories," where it is rated Class B. Used as a single-input preamp between a laptop source and a pair of Rogue M180 monoblocks in EL's main system, the DACport produced a large soundstage, a slightly rolled-off but grain-free treble, and a tube-like midrange. Compared to the Benchmark DAC1 HDR, the DACport lacked resolution and bass weight, but always sounded musical and tonally balanced. LX version sounds clearer, more transparent, and is rated Class B as a D/A processor. A less expensive version of CEntrance's DACport, the LX dispenses with that model's volume control and can be used as a regular USB D/A processor. Like the original, the LX operates in adaptive isochronous USB mode rather than the theoretically better asynchronous mode, but nevertheless performed well on the test bench, showing no jitter-related sidebands. Compared to the original DACport, the LX offered a similarly smooth and grain-free treble, but was slightly clearer and more transparent. However, the LX couldn't match the smoothness or superb sense of space provided by the significantly more expensive Halide DAC HD. "CEntrance's DACport LX offers superb sound quality at an affordable price," concluded JA. (Vol.33 Nos.6 & 10, Vol.35 No.10 WWW)

Channel Islands Audio Transient Mk.II: $699
Housed in a small (4.45" W by 2.9" H by 5.25" D), nicely finished aluminum case, the Transient Mk.II is an asynchronous USB DAC with a 24-bit volume control and three digital outputs: S/PDIF via 75-ohm BNC, I2S via mini-DIN, and differential I2S via an HDMI jack. Six front-panel LEDs indicate the incoming signal's sampling rate: 44.1, 48, 88.2, 96, 176.4, or 192kHz. In a case identical to the Transient's, the optional VDC5 Mk.II high-current power supply ($329) feeds the Transient a linear 5V DC at 2.5A for reduced noise and ripple. Though it lacked some high-frequency focus and ease, the Transient Mk.II produced a well-balanced overall sound, with good soundstage size, respectable bottom-end heft, and a clean midrange, said JI. Measured performance was somewhat disappointing, however; JA found that, even with 24-bit data, the Transient offered resolution of just over 17 bits. (Vol.37 No.3 WWW)

iFi Audio iDAC: $299
iFi Audio is a subsidiary of Abbingdon Music Research. The iDAC, iFi's first product, is a sleek, single-box D/A converter built into a 6"-long aluminum extrusion with an attractive textured finish. It uses an ESS Sabre DAC chip capable of handling resolutions up to 24-bit/192kHz, and has a single USB-B input, a pair of RCA jacks for line output, and a 3.5mm headphone jack with volume control. It can be powered by the user's computer or by iFi's iUSBPower 5V power supply ($199). Compared with the AudioQuest DragonFly, the stock iDAC had a better overall sense of touch on strings and percussion, and revealed greater richness and complexity in hi-rez music files, said AD. With the iUSBPower powering the iDAC, Art noted a subtly clearer sense of force in note attacks and better spatial presence around voices. "Highly recommended," he concluded. (Vol.36 No.5 WWW)

Meridian Explorer: $299 $$$
Made in England, the Explorer is a 4"-long USB D/A headphone amplifier built into a lightweight aluminum-alloy tube with a hard-anodized finish. A plastic cap at one end incorporates a USB mini-B jack, while a similar cap at the other end holds two 3.5mm jacks: one for headphones, the other for line-level audio output. The Explorer operates in asynchronous mode and has a 24-bit/192kHz Texas Instruments PCM5102 converter chip; three small LEDs on the Explorer's upper surface indicate the sample rate of the incoming music file. Its 130mW headphone output incorporates a 64-step analog volume control, while the line-output jack is fixed in level. Though it lacked the Halide DAC HD's timbral richness, the Explorer had an airier overall sound, with detailed highs, a good sense of scale, and generous lows, said AD. JA noted "generally superb" measured performance. (Vol.36 No.9, Vol.37 No.10 WWW)

Musical Fidelity M1DAC: $799 $$$ ✩
The M1DAC digital-to-analog converter uses two dual-differential Burr-Brown D/A chips, has a choke-regulated power supply, and offers coax, TosLink optical, AES balanced, and USB inputs, as well as standard RCA and balanced XLR outputs. While its USB input is limited to 16-bit/48kHz data, the M1 can handle any S/PDIF signal at sample rates up to 192kHz. With its astonishingly low noise floor, the M1 produced outstanding low-level resolution, crisply articulated transients, rhythmic certainty, and tonal purity. "A stunning bargain," ST decided, adding that this DAC "goes for a song but has a very, very low noise floor. The sound quality is highly resolving and, at the same time, non-fatiguing." Compared to the Rega DAC, the M1DAC lacked tonal richness but sounded lighter and quicker, with an airier top end and more space between the notes, said ST. The M1DAC demonstrated superb rejection of jitter on all its inputs and offered overall measured performance that was close to the state of the art, found JA. Borderline Class A but "You will need a very, very good system to realize how great this DAC is!" warns ST. Latest version has a revised power supply and uses the popular Texas Instruments TAS1020B USB receiver, operating in the optimal asynchronous mode, to handle resolutions up to 24-bit/96kHz. While the measured performance of the original M1DAC was marred by low-level power-supply spuriae, the latest sample produced a much lower noise floor, found JA. (Vol.34 Nos.3, 5 & 6, Vol.36 No.1 WWW)

Rega DAC-R: $1195 $$$ ✩
Rega's DAC measures just 8.4" W by 3.1" H by 10.5" D and sports an attractive aluminum-and-steel case with a reflective front panel. It offers two coaxial, two optical, and one USB input, as well as 10 digital filters: five for data rates of 48kHz and under, five for rates up to 192kHz. While it operates in the adaptive USB mode and its Burr-Brown PCM2707 USB receiver chip is limited to resolutions/sample rates of 16-bit/48kHz, the Rega DAC "had a richness, a fullness of tone, an analog sense of ease, that I had not hitherto heard from digital, save for SACD," said ST. Compared to the Musical Fidelity M1DAC, however, the Rega DAC lacked some air and openness in the top end. JI was puzzled by its warm balance but ST is adamant that the Rega DAC is a reference product: "Probably the most analog-like sound Sam has heard from a DAC. The filter settings allow the user to change the soundsignificantly, says Sam, slightly according to Rega. Sony was right: CD forever!" Compared with the Peachtree iDac, the Rega had a warmer, fuller sound, but lacked clarity and accuracy, said JI. JA's measurements confirmed that the Rega DAC operates in isochronous adaptive mode. The Rega's respectable measured performance was marred by supply-related jitter sidebands that may have contributed to the DAC's weighty low frequencies. (Vol.34 Nos.5 & 10, Vol.35 No.2 WWW)

Schiit BiFrost: $349
Made in the US, the Bifrost is a solid-state D/A processor with three digital inputs (coaxial, TosLink, asynchronous USB) and a pair of RCA output jacks, housed in an attractive brushed-aluminum chassis. It uses a 32-bit delta-sigma AKM4399 chip coupled with a fully discrete JFET analog section and handles signals of any resolution up to 24-bit/192kHz at all of its inputs. Compared with the AudioQuest DragonFly, the Bifrost produced a larger, more open soundstage, with more depth and improved layering of instruments; compared with the Benchmark DAC1, the Schiit traded resolution and accuracy for natural musicality, said JI. "The Schiit Bifrost is a carefully designed and beautifully built DAC," he decided, recommending high Class B. Uber Analog stage adds $70, Gen 2 USB input adds $100. (Vol.36 No.8 WWW)

Wadia 121decoding computer: $1299
The 121decoding computer is a solid-state, remote-controlled D/A processor and headphone amplifier housed in a compact (8" W by 2.7" H by 8" D) case of black powder-coated aluminum. It has balanced and unbalanced outputs, BNC and RCA coax digital inputs, TosLink and asynchronous USB input jacks, a three-pin AES/EBU socket, a seven-pin connector for the external power supply, and a front-panel headphone jack. All digital inputs can accept data rates up to 24-bit/192kHz. Compared with the Benchmark USB DAC, the Wadia lacked bass definition and overall clarity; compared with the M2Tech Young, the Wadia sounded pleasant and polite, but lacked resolution, said JI. On the test bench, the Wadia's AES/EBU input behaved correctly, but its S/PDIF and USB connections failed to output 24-bit resolution. (Vol.36 No.7 WWW)

Wavelength Proton: $599 $$$ ✩
Designed by Gordon Rankin, the Proton is a solid-state DAC built into a small (4" W by 2.5" H by 5.75" D), attractive aluminum extrusion. It has a single USB type B input, operates in isochronous asynchronous mode, handles resolutions up to 24-bit/96kHz, and uses a Wolfson XWM8721 DAC chip that also incorporates an analog volume control and headphone amplifier. Though it was a bit less dynamic and dramatic than Wavelength's more expensive Cosecant, the Proton had a naturally colorful and textured sound, said AD, who bought the review sample. "An easy recommendation," he said. The Proton's limited dynamic range is due to the use of a battery supply with limited voltage capacity, JA noted. Compared to the AudioQuest DragonFly, the Proton sounded slightly less brilliant, lacking some treble extension, openness, and presence, said AD. (Vol.34 No.10 WWW; Vol.35 No.10 WWW)

C

Arcam rBlink: $249
The rBlink is a very small (2.9" W by 1" H by 3.9" D) Bluetooth audio receiver and digital-to-analog converter with RCA analog and S/PDIF coaxial outputs. It uses Arcam's implementation of CSR's audio-optimized aptX Bluetooth codec and a Burr-Brown PCM5102 DAC chip. Installation was simple and the Bluetooth sound was always easy to enjoy, said Sam. "Highly recommended," he concluded. JA's measurements of the rBlink suggest that its sound quality will very much depend on the codec used to stream audio data to it; the AAC codec appeared to preserve resolution at the expense of noise-floor modulation and enharmonic spuriae, while the aptX codec sacrificed absolute resolution in favor of preserving a random noise floor. Though data streamed via Bluetooth sounded somewhat brash and compressed vs that same data sent via a TosLink connection, the rBlink was surprisingly enjoyable, said JA. "Plug the Arcam's S/PDIF output into your high-end D/A processor and you have a convenient and legitimate source of music," he concluded. (Vol.36 No.12, Vol.37 No.3 WWW)

Audioengine D3: $149 $$$
The Chinese-built Audioengine D3, like the physically similarand similarly portableAudioQuest DragonFly, is a combination D/A converter and headphone amplifier with a USB standard A plug at one end and a three-conductor, 3.5mm mini-jack at the other. Its shiny aluminum case conceals an Asahi Kasei Microdevices AK4396 converter chip, a Texas Instruments LM49726 op-amp, and TI's popular TAS1020B USB receiver, with firmware for asynchronous streaming. Headphone users will delight in knowing that the Audioengine's price includes a 3.5mm-to-1/4" jack adapter; those who wish to drive their audio systems with the D3's 2V RMS output must supply their own miniplug-to-RCA-plug cables. SM considered the D3, fresh out of the box, "too sharp on top"even when he factored in the inherent top-end emphasis of the Skullcandy Aviator 'phones he was using. But the brightness moderated over time, "though not at the expense of [the D3's] intoxicating speed and vibrant high-frequency color." (Vol.37 No.4 WWW)

Sonos Connect: $349 ✩
Sonos Connect:Amp: $499 ✩
More sophisticated than the Squeezebox," said JA. The user-friendly Sonos system sets up its own proprietary, encrypted audio network and can even dispense with the partnering computer if necessary, working with a network-attached storage hard drive that can operate as a standalone source of media files. Installation "couldn't have been easier," said JA. While he found the ZP80's analog outputs to be adequate for use in noncritical applications, JA felt the Sonos performed best with its digital output feeding an external DAC. Rating refers to the performance of the ZP80's analog outputs. Testing of the new ZP90 and ZP120 versions continues the recommendation. The ZP90 is now called the Sonos Connect. Review was of the very similar ZP80 and ZP100, respectively. While the ZP120 (now called the Connect:Amp) resembles Sonos's original ZP100 in using a class-D output stage, it offers slightly more power (55 vs 50Wpc), replaces the linear power supply with a switching supply, and provides more robust wireless networking capabilities. Though limited to sample rates of 44.1 and 48kHz, the ZP120 exhibited a well-managed gain architecture and performed admirably on the demanding high-frequency modulation test, found JA. Remote control app for the iPhone and iPod Touch dramatically improves user interface. (Vol.29 No.10, Vol.33 No.4 WWW)

D

Apple AirPort Express: $99 $$$ ✩
While the Airport Express works only with iTunes v4.6 or later (running on both PCs and Macs), is limited to 16-bit data, and functions only at a 44.1kHz sample rate, the combination of iTunes and the Airport Express offered an easy way to pipe CD-quality music around the entire home. "The beauty of this unassuming component," said JA, "is its S/PDIF data output, which allows the Airport Express to assume a respectable role in a true high-end audio system." However, its lack of an internal clock can lead to the first couple of seconds of songs being missed with DACs that are slow to lift their mutes. (Vol.28 No.5 WWW)

ASUS Xonar Essence ST: $199.99 ✩ ASUS XONAR Essence STX: $189.99 ✩
Soundcards compatible with PCI (ST) and PCI Express (STX) personal computers running the Windows XP, Vista, and 7 operating systems (Macs not supported). The Xonar Essence boasts a specified signal/noise ratio of 124dB, and its analog output circuitry is shielded by a grounded metal cover, preventing RF interference from contaminating the audio signal. In addition, the Essence draws its power from a 4-pin socket separately connected to the PC's power supply, thus isolating the analog circuitry from the PC's motherboard. The soundcard offers a headphone output, a line/microphone input, and standard and optical S/PDIF digital outputs, but there is no digital input. D/A conversion is handled by a high-quality 24-bit Burr-Brown PCM 1792. Though the Essence could not support 88.2 or 176.4kHz files through its analog inputs, JA was impressed by the card's weighty lows, clear midrange, and airy highs: "I can unreservedly recommend the Xonar Essence as the least expensive means of extracting true high-end sound from a PC." A driver update guarantees bit-perfect playback from the digital output at all sample rates up to 192kHz, and, unlike with the earlier driver, ASIO-compatible applications take exclusive control of the audio device. (Vol.33 Nos.1 & 9 WWW)

The digital processors are DACs or things to route digital sound somewhere. There is some overlap if there's a CD player with inputs to its DAC, and some overlap with preamp/DACs, some of which of those might have some additional, secondary digital EQ functions.

The signal processors are mostly about varieties of digital EQ, with again a few hybrid products having some secondary functions.

The separation seems clear enough to me. It is the whole universe of modern audio which seems complex, i.e., the products themselves.

Interesting that Digital Processors and Signal Processors are separate categories, given that I encounter the term 'DSP' (Digital Signal Processor) so often.

The Digital Processors category is almost exclusively digital/analog converters. The Signal Processors category is reserved for things that do something to the signal and includes analog-domain processors, such as the BSG Q0L.

I'm going to profess a bit of ignorance here, so .... one of the places where DSP or some variant shows up in my world is related to music players such as built into the Pono device, or in computer software such as Foobar2000 etc. The great thing about EQ included in these players (or as plug-in software) is that the digital data gets EQ'd before it hits the DAC, so that whatever DAC or amp is used, the EQ remains constant in playback. Ignoring any negative impact on the EQ due to which peripherals are used, I've always assumed that EQ pre-applied to the digital data as described will reduce the resolution of the playback. If that's true, are there common analog EQ solutions that would provide better sound?

From your comments prefacing the Recommended Loudspeakers 2015, I understand that category A (Full Range) has LF extension down to 20Hz. What about B (Full Range) and C (Full Range)? Do they also need to have LF extension down to 20Hz? If not, what is the LF extension for inclusion? For the restricted LF I assume that LF extension is to 40Hz for all categories. Clarification will be helpful and appreciated.

Despite there being 25 Class A preamps, there are only 2 Class B preamplifiers (both from the same company) and NO class C Preamps? There are 18 Class A Power Amps and Zero Class C or D Power Amps? I thought, "Perhaps there are just no products that fit those categories any more. No more Adcom's. No more B&K's." But then I looked around and found that there ARE musically satisfying budget electronics.

So I am left to wonder...do they no longer submit their products for review or is Stereophile no longer interested in reviewing them?

I began reading Stereophile in my 20's when there was no way I could even consider a $10,000 amplifier. I aspired to a system like that, but also loved reading about gear that I could stretch to afford. I loved building a musically satisfying SYSTEM for well under $10,000. Had I only been able to read about the gear that was so far out of reach, I would likely have dropped the hobby altogether. Without the bridge, I would never have been able to get across to the ultimate destination. That bridge is being taken away from the next generation of Audiophiles.